As for tightening them, I was just going to tighten them as I tightened the screws you installed. Wort comes to worst I would drill out the holes in the hub and then use a pair of needle nose pliers with some shrink tube on them so as not to mar up the surface...
As for cost... um.. I'm in it a grand now and it's nowhere near finished, I still have to buy the MFU, I'm looking at around $400 to $600 for a paint job. Plus the grill, tanks, about $250 in small detail parts. Lets not forget 300 LED's.
Heck whats a few more bucks for lug nuts.
I got a new drill press for Christmas I might try to make them myself. I want a different type for my truck.
I think the hardest part would just be the size. They would have to be between 1/4" and 5/16' long and probably 4-5mm round. Be a pain to drill and tap.